Unless a willingness exists to embrace mass transportation and, thus, decrease the use of personal automobiles, traffic delays will be a growing and unfortunate fact of life. Ultimately, mass transportation systems will become a more significant part of everyday travel due to population growth and the costs (personal and environmental) associated with highways packed with automobiles-each carrying one person. One of the costs comes in the form of highway congestion and the anguish that accompanies long traffic delays. However, until more convenient and cost-competitive, mass transportation systems become available, it is desirable to improve the highway congestion problem, and nowhere is it worse than around toll booths.
The use of toll booths on highways is viewed as a mixed blessing by motorists. Most will agree that safe, high-speed, well-maintained highways are vital to the quality of their life; that such highways are expensive; and that toll booths provide an equitable way to pay for them. On the other hand, most will agree that stopping in order to pick up a ticket and/or make a payment is an annoyance, particularly during peak traffic periods when toll payment queues exceed several minutes. The fuel wasted and pollution created, while waiting in a queue, is significant when large numbers of automobiles are involved. Considering the many conveniences available in present day automobiles and the generally high quality of toll roads, the annoyance displayed by motorists when encountering a traffic delay is somewhat surprising. Nevertheless, the desire for increased transit speed appears insatiable.
U.S. Pat. No. 4,338,587 discloses a vehicle toll collection system that automatically identifies vehicles in an "express" lane. In order to benefit from the express lane, vehicles are equipped with radio frequency transmitters that send data to electronic toll collecting apparatus to identify the vehicle using information such as the state of registration and license number. Tolls are billed to the vehicle owner's account, and payment is disbursed by an agency that both issues license plates and collects toll payments (in advance) from the vehicle owner. Although this technique is useful, it requires a great deal of administrative overhead and is susceptible to fraud. For example, the transmission of incorrect information (the license number of another vehicle) is not detected until the next time the owner of the other vehicle is billed.
U.S. Pat. No. 4,963,723 discloses an automatic toll collector for toll roads which requires the driver of a vehicle to insert an integrated circuit (IC) card into each toll booth. The IC card stores both license and bank account information. Tolls are withdrawn from the card holder's bank account, and means are provided for comparing the license information with the actual license plate which is acquired as the vehicle passes through the toll booth. However, this system offers little or no improvement in the speed of toll collection since the driver is required to stop. But even if the information on the IC card were electronically transmitted to the toll booth, the improved security against fraud comes at great inconvenience to both the card holder and the highway authority. Card holders should be able to pay the toll for any vehicle that they happen to be in (a friend's car, a rental car, etc.), not just specific vehicles; and additional equipment is needed to read each license plate. The latter is not only a significant technical challenge but also requires cooperation among various states regarding license design if out-of-state drivers are to benefit from such a system.
One popular technique for making high speed toll payments is through the use of a miniature transponder that attaches to the windshield of a vehicle and broadcasts an identification signal when it enters an electromagnetic field having predetermined characteristics. Because such transponders operate at radio frequencies, they have become known as RF-tags. Unfortunately, electronic eavesdropping is relatively easy in such a system; the transmitted identification signal can be intercepted, recorded, and rebroadcast by another vehicle to avoid toll payments. It appears to be a fact of life that when theft is too easy to accomplish, even the most honest people indulge; and when theft requires great effort, even scoundrels behave.
In systems where payments are made by the transfer of data, care must be taken to assure that the data represents an accurate indication of the purported information. Tampering with the device containing the data can produce various undesirable results that comprise the integrity of the data and thereby defeat the payment scheme. For example, if the account number on a credit card is altered, then the transaction is charged to the wrong person; and if the cash balance on a debit card is increased in an unauthorized manner, then the creditor is defrauded. It is therefore desirable to provide a secure toll collection scheme for moving vehicles.